Stream your sound
Or in other words "the 3 S's"
Sound, Sync, and Stream.
From Instance, choose the sound Tab.
Go to sync, and choose stream.
Go to your timeline insert keyframe in the sound layer. And drag it till you want the sound to stop, or the end of your movie.
This will reduce your file size to around 500-700kb.
Happy Flashing:)
iLLiCit147